I'm scared. Post-reconditioning the HVB overcharged and warbled.

Hey Folks,

I'm trying to figure out if my car toasted the good modules by bringing them to >9v.

I didn't think it was possible, and it made a scary sound like arcing underwater (or what I imagine that would sound like). No smell, no smoke, and the temp sensors are happy.

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I did a 3 cycle reconditioning with prolong charger & discharger to 134v.

Block 5 was suspected before hand, but I opted for stress testing it during reconditioning to see if it would bounce back or not. I've had modules bounce back before or degrade further. (Not best practice perhaps, but more convenient than tearing down the HVB for module swapping)

So the cycles finish, I put the car into neutral to bleed off some overcharge from final top balance.

I fumble with Dr. Prius and Torque for a few minutes because OBDII doesn't want to pair sometimes. I'm blind and I don't like it.

I kick her into drive and go around the block, still blind, and then it pops a PA080 as noted by dashboard christmas. I pull over and finally OBDII connects.

This is what I saw:

Ok block 5 bad. Swap required.

I drive a short ways back home. I try to bleed off some of that charge with neutral AC again because 100% SoC is uncomfortable.

Something is wrong. It's now dropping super fast and I try to combat this by putting her back into drive:


In retrospect, the module voltages were fine and I should have turned the car off here... I don't know why SoC is reading that low, but fine.

Instead I kept her in drive:


Until this happened:


Queue scary sounds from the back.

So am I probably ok to continue with the plan to swap out block 5? Or does anything think I may have toasted the other blocks? Or some other component? Would the bad block's modules potentially make the scary sounds?

Thanks in advance,
I read this forum all the time.

 

I'm still struggling to understand why the car would allow this to happen. If the whole pack is toast now that's super depressing.

 

Updated plan:

I just purchased a Tenergy T180 100W hobby charger and 25ft of 16 gauge copper wire.

While prolong does work for balancing, I want more insight into the capacity of the individual modules so I can pair them into blocks better.

Furthermore, I have 10 or 12 spare old modules I deemed as bad (from previous swaps) which with more delicate cycling might not be as bad as I thought. After all, they also were never capacity tested individually.

So the plan is to capacity test every module I have through 3-5 cycles down to 6v, pair them better, and balance with copper wire in parallel.

If anyone thinks 6v is too low, maybe 6.10v or 6.30v is better, I'd love to hear from you.

Sidenote: I did see someone overcharging a module to 9.1v with a hobby charger, and they said it does swell however it also un-swells and remains functional as long as it is in the pack (and mine were considering the car was running). That gives me some hope.

Also, sorry for the triple post. I can't find the edit button on the previous posts.

 

Went to storage today to pick up my spare modules.

13 total modules. 2 broken modules (missing post & doa cracked from ebay where the seller replaced it).

5 modules read below 7.2v.
6 modules read 7.2v or higher.

These were stored for over a year, possibly closer to 2 years. I was surprised that so many modules held 7.2v.

Edit: I guess that makes some sense, since I swapped blocks where it's entirely possible only 1 module in a block was faulty.

Tenergy hobby charger arrives tomorrow, so I'll get the pack out of the car and then test the polarity of the pack modules in case any of them flipped.

Then I'll repack the 11 spare modules for capacity testing & individual reconditioning, logging results in a spreadsheet.

Edit: I want to practice with the Tenergy on the low reading spare modules but will eventually capacity test all the modules in the pack as it is now, with the exception of block 5 which I'm just going to write off entirely as a loss.

 

Ok so first of all, every spare module has electrolyte crust on the negative post. Hoping I can clean those up.
(You can see the left most module where I wiped it with a towel, though there is still some crust around the edge)


The bus bars on the pack are clean as a nickel, because they ARE nickel. *badum-tss*


Not to say that there isn't corrosion, there is, behind the nuts. Especially on the special connection attached to block 5!


So I believe the proper action is to sand off the corrosion, gently, and pray that it doesn't reach the BCU.

But I will do that later. For now I'm going to...

- read voltages of the pack modules as they are now
- clean up the electrolyte crust from posts on the spares with towels and not vinegar
- weigh the spares to see if any happen to read higher or lower (electrolyte mass measurement?)
- re-pack the pack modules in parallel orientation (but not connected), sans block 5, replaced with 2 spares
- Tenergy capacity test of pack modules

Sidenotes:

- The HVB is so much easier to remove from the car without the main shielding, I can't believe I didn't do that in previous efforts because that extra inch of clearance means everything.
- I cannot see any swelling, but it's not like there would be much room for it while packed so I'm not sure what to look for. There isn't any "sludge" near the bottom of the modules from my first look around (like I've seen in other posts on this forum about leaking).

Update:

The Tenergy didn't come with a banana to alligator clip cable, so now I get to wait 2 more days for Amazon. I went with these in case it is helpful to anyone in the future. AWG unknown, but one review mentions use with 30V @ 5A and another with 25A (unknown V). Rated for 15A/1000V, but I won't be pushing it over 5A anyway. Definitely appears to be a better choice in a sea of terrible products on Amazon.

 

Ok so from what I can tell, peak delta detection doesn't work with prius modules, so I'm playing it safe...

First, manual cycling! Laborious, but safe.

1) Top up starting charge from 7.2V (or ?.??V) to 8.6/8.7V @ 5A, attended, cutting off when voltage visibly peaks/plateaus in the graph
----------------
2) Discharge #1 to 6V @ 6.5A (but apparently it should be to 5.7/5.8V, because the hobby charger's reading is off, I'll double check this shortly)
3) Charge #1 @ 6.5A to 4400mAh, then @ 0.3A to 2000mAh (the intention is to reduce stress on the top end, mirroring as close as possible prolong charger's amperage, because ppl are crazy trying to pump 6500mAh or more into modules that can't hold that much)

I don't know how much will be lost to heat, but I'm hoping less by using low amperage on the top end. What really matters is what happens next...

4) Discharge #2 to 6V @ 6.5A
5) Charge #2 " "
6) Discharge #3 to 6V @ 6.5A

I have a prolong, so I'm more interested in measuring capacity in order to better pair modules into blocks.

If I don't need to do step 1, that'll save a small bit of time, but I'm under the impression you should always discharge to 6V only from a full charge, ideally a top balanced full charge.

Edit: Discharge is capped at 5A with the Tenergy T180.

 

Jeez. The Tenergy T180 only discharges at 2A. So I guess I get to buy another thing!

A 250W 35A discharger that makes pretty charts. Oooh la la.

New plan might be to top balance with prolong, then capacity test all the modules with the fancy discharger.

I'm really most interested as I said in capacity testing for pairing purposes.

 

Yessir. I have 14 AWG with a 0.02V drop from the reading on the charger. It's actually higher than the voltage at the terminals.

 

Prolong's documentation for the light bulb discharger says 200W down to 140V (5V per module, less than I'll be taking them for capacity testing).

Prolong's documentation says: "During these first two phases of the discharge process, the load (light bulb wattage) on the battery does not matter. The battery regularly sees 50A and higher, so the ~1.5-3A delivered by using 200W bulbs in the discharger is safe."

3A is still very slow. I'm not trying to be reckless here but would 6.5A or 10A be ok? If I understand, you get more meaningful results from capacity testing with higher amperage, since that's what the car will actually be doing in real life.

Edit: 8A feels like a good middle ground, because while the cables are thick I still don't really want to push it.

 

Heehee. I've spent more on tools than modules. (and it's been almost 3 years)

1 of the modules in block 5 is bad. I could get back on the road tomorrow if I just swap it and top balance with prolong.

But... I want to capacity match the blocks this time and have a deeper understanding of the health of the pack.

So far I've been pretty lucky. Only need to swap a module once a year, but I'd really like to only need to swap a module once every 2 or 3 years. A guy can dream, right?

 

I'm excited to try out the new strategy:

1) Prolong charge & balance the pack
2) Quick discharge the 28 modules to 6V, making note of discharge capacity for each

Repeat 3 times.

20 hours (less than typical fill and balance because it's not as deep a discharge as the PD [4.78V light cycle])
+ 21 hours (let's say 45 min quick discharge per module)
+ 7 hours (time spent tending to the process, 15 minutes per module)
+ 30 minutes (time spent nutting and de-nutting the harness)

= 48.5 hours or less, with 7.5 hours of management

In a timeline, that looks like...

Starting on Monday at Noon, discharging 14 modules from Tuesday at Noon to Midnight, doing that again on Wednesday, with first pass capacity results ready on Thursday, where the cycle can start again.

So it would be 3 days per cycle.

Bypassing the problems with overcharging and the slowness of a single hobby charger.

Thoughts?

 

Right. This is precisely why I'm switching over to prolong for the charging. The cooling is already there in a sealed pack (and prolong utilizes it). I won't use the T180 for charging or discharging. 17 days for 3 cycles without sleeping is insanity. 9 days with sleeping is manageable. Also with the new method there isn't a need for a 1 hour wait between cycles, except for the final module discharged in the pack.

Charging with T180 risks overcharging, heat, and scrapification. But does discharging at 6.5A to 8A also risk heat damage without adequate cooling? That would be the new concern. The room is a garage which is the coolest room in the house, door slightly open, probably 60ish F. (I'm not in Hawaii anymore)

Thank you for your time.

 

If I'm reading this correctly, S Keith said 13A discharge is doable.